This invention relates to a backflow preventer.
Backflow preventers are principally used for preventing contamination of a public water distribution system by preventing backflow or back-siphonage of contaminated water into the system. Usually, the backflow preventer assembly is installed in a pipeline between a main supply line and a service line that feeds an installation, e.g., hotels, factories or other institutions, or even a multi or single family residence. A backflow preventer assembly typically includes two check valves permitting flow only in the direction from the main supply line to the service line.
In one aspect, the invention features a backflow preventer assembly including a housing having a first end and a second end, a first mounting assembly configured to removably secure a first check valve adjacent the first end of the housing, and a second mounting assembly configured to removably secure a second check valve adjacent the second end of the housing. The housing includes a wall having an inner surface defining a through bore extending between the first end and the second end. Each mounting assembly has a wall with an inner surface defining a through bore in fluid communication with the housing through bore. A first coupling secures the first mounting assembly to the housing, and a second coupling secures the second mounting assembly to the housing.
Embodiments of this aspect of the invention may include one or more of the following features.
The first and second couplings are solder joints, weld joints, or clamps. Alternatively, the first coupling includes threads on the inner surface of the housing wall adjacent the first end of the housing and threads on an outer surface of the first mounting assembly, and the second coupling includes threads on the inner surface of the housing wall adjacent the second end of the housing and threads on an outer surface of the second mounting assembly.
In another illustrated embodiment, the first coupling includes a flange on the first mounting assembly and a flange at the first end of the housing for coupling to the first mounting assembly flange, and the second coupling includes a flange on the second mounting assembly and a flange at the second end of the housing for coupling to the second mounting assembly flange. Alternatively, the first coupling includes a circumferential groove on the first mounting assembly and a circumferential ridge at the first end of the housing wall, and the second coupling includes a circumferential groove on the second mounting assembly and a circumferential ridge at the second end of the housing wall.
The backflow preventer assembly further includes plating material located on the inner surface of the housing and the inner surface of the first mounting assembly. The plating material is a metal coating, e.g., nickel, or a polymer coating, e.g., polyurethane.
The backflow preventer assembly further includes a first ball valve assembly attached to the first mounting assembly and a second ball valve assembly attached to the second mounting assembly. The first mounting assembly and the second mounting assembly each includes an inner end and an outer end. The outer ends of the first mounting assembly and the second mounting assembly are threaded, and the first ball valve assembly is threadedly attached to the outer end of the first mounting assembly and the second ball valve assembly is threadedly attached to the outer end of the second mounting assembly.
An outer surface of the housing wall, an outer surface of the first mounting assembly wall, an outer surface of the first ball valve assembly, an outer surface of the second mounting assembly wall, and an outer surface of the second ball valve assembly include plating material. An inner surface of the first ball valve assembly and an inner surface of the second ball valve assembly include plating material.
The backflow preventer assembly further includes a first check valve assembly attached to the first mounting assembly and a second check valve assembly attached to the second mounting assembly. The first mounting assembly and the second mounting assembly each includes an inner end and an outer end. The inner ends of the first mounting assembly and the second mounting assembly are threaded, and the first check valve assembly is threadedly attached to the inner end of the first mounting assembly and the second check valve assembly is threadedly attached to the inner end of the second mounting assembly.
The housing wall defines an access port, and a cover closes the access port. The backflow preventer assembly includes a plurality of test cocks.
A pressure reduction assembly is in fluid communication with the housing through bore, and a connection assembly secured to the housing wall attaches the pressure reduction assembly to the backflow preventer. The connection assembly includes a union nut. The housing wall includes an outward extension for attachment of the pressure reduction assembly thereto. The outward extension defines a through bore.
In another aspect, the invention features a backflow preventer assembly including a housing having a first end and a second end, a wall having an inner surface defining a through bore extending between the first end and the second end, and a connection assembly. The housing wall includes an outward extension defining a through bore in fluid communication with the housing through bore, and the connection assembly is secured to the outward extension for attachment of a pressure reduction assembly thereto. The connection assembly includes a union nut and a cylindrical tube. The cylindrical tube has a first end axially inserted into the through bore of the outward extension and a second end with a rim configured to retain the union nut.
In another aspect, the invention features a method of mounting ball valves and check valves to a backflow preventer. The method includes securing opposed surfaces of a first mounting assembly and a housing with securing material, and securing opposed surfaces of a second mounting assembly and the housing.
Embodiments of this aspect of the invention may include one or more of the following features.
An inner surface of the housing, an inner surface of the first mounting assembly, and an inner surface of the second mounting assembly are plated with plating material. The plating material forms a wall restricting migration of the securing material into a bore of the housing, a bore of the first mounting assembly, and a bore of the second mounting assembly.
The method further includes threadedly attaching ball valve assemblies to the outer ends of the first and second mounting assemblies, and threadedly attaching check valve assemblies to the inner ends of the first and second mounting assemblies.
In another aspect, the invention features a method of mounting valves to a backflow preventer including securing opposed surfaces of a first mounting assembly and a first end of a housing, securing opposed surfaces of a second mounting assembly and a second end of the housing, removably attaching a first check valve assembly to an inner end of the first mounting assembly, and removably attaching a second check valve assembly to an inner end of the second mounting assembly.
Embodiments of this aspect of the invention may include one or more of the following features.
The method further includes removably attaching first and second ball valve assemblies to the outer ends of the mounting assemblies. The opposed surfaces of the mounting assemblies and the housing are secured together with securing material. The mounting assemblies and the housing are threaded, bolted, clamped, or crimped together. The check valve assemblies are threadedly attached to the mounting assemblies, and the ball valve assemblies are threadedly attached to the mounting assemblies.
The method further includes plating an inner surface of the housing, an inner surface of the first mounting assembly, and an inner surface of the second mounting assembly with plating material.
Advantages of the invention include a backflow preventer assembly that is less expensive to manufacture than currently available backflow preventer assemblies for similar applications, and permits easy service and replacement of the check valves and ball valves.
Other features and advantages of the invention will become apparent from the following detailed description and from the claims.